The present application generally relates to extremum seeking control strategies. The present application more particularly relates to regulating, via extremum seeking control, the amount of air that is flowing through a heating, ventilation and air conditioning (HVAC) system in order to reduce the amount of mechanical heating and cooling required within an air-handling unit (AHU).
Extremum seeking control (ESC) is a class of self-optimizing control strategies that can dynamically search for the unknown and/or time-varying inputs of a system for optimizing a certain performance index. It can be considered a dynamic realization of gradient searching through the use of dithering signals. The gradient of the system output with respect to the system input is typically obtained by slightly perturbing the system operation and applying a demodulation measure. Optimization of system performance can be obtained by driving the gradient towards zero by using an integrator in the closed-loop system. ESC is a non-model based control strategy, meaning that a model for the controlled system is not necessary for ESC to optimize the system.
An abrupt change in the operation of the plant of a traditional ESC system can cause an undesirable delay while the ESC adapts to the new optimal settings for the system. Where ESC is utilized for HVAC economizer applications, this may correspond to additional power being consumed by the AHU.